The present invention relates to a vehicle seat adjustable into a plurality of seat adjustment positions and having a back support and a seat cushion which is subdivided into a plurality of individual upholstery elements separated in a transverse direction of the seat. The upholstery elements are connected together and displaceably arranged relative to one another for seat depth adjustment in guides extending in a longitudinal direction of the seat.
In a vehicle seat shown in German Published Unexamined Patent Application No. 3,226,101, the seat cushion has a fixed rear seat cushion part facing towards the seat back and a front seat cushion part which can be displaced in the longitudinal direction of the seat relative to the rear seat cushion part. In order to improve seating comfort by providing leg support, the displaceability of the front part of the seat cushion is used to match the seat depth of the vehicle seat (extending in the longitudinal direction of the vehicle) to the varying thigh lengths of the passengers, which generally fluctuate between 450 mm and 550 mm and can be as much as 600 mm. At maximum seat depth adjustment, however, there is a relatively large gap, of more than 150 mm at times, between the front and rear parts of the seat cushion. The upholstery regions boundering such a wide gap are felt as uncomfortable edges, even with a relatively soft design of the seat cushion upholstery.
In another vehicle seat described in German Published Unexamined Patent Application No. 3,018,323, the seat cushion is subdivided into a multiplicity of individual upholstery elements. The individual upholstery elements are connected together to form an upholstery chain which is connected, at one end, to the seat back and, at the other end, via a tension spring to the passenger compartment structure. In order to adjust the seat depth, the seat cushion has to be displaced relative to the fixed seat back in the longitudinal direction of the seat. This causes gaps or recesses of varying width to form between the individual upholstery elements. Due to the spring tensioning of the upholstery chain, the individual upholstery elements can also be displaced relative to one another due to body movements, (associated with powerful vehicle acceleration or vehicle deceleration, for example) so that, on the one hand, the person seated has a feeling that the seat is floating and, on the other hand, the width of the seat gap can continuously change and therefore become noticeable. Both effects are uncomfortable to the person seated and have a substantially adverse effect on the seating comfort.
An objective of the present invention is to improve the seating comfort of a vehicle seat which is adjustable into a plurality of seat adjustment positions having a seat cushion which is subdivided into a plurality of individual upholstery elements separated in a transverse direction of the seat, these upholstery elements being connected together and displaceably arranged relative to one another for seat depth adjustment.
This and other objectives are achieved in the present invention by providing a vehicle seat having a seat cushion which is subdivided into a plurality of individual upholstery elements which are displaceably arranged relative to one another in a longitudinal direction, with coupling means for coupling the upholstery elements such that a gap appears during seat depth adjustment between each said upholstery element, wherein each gap has an approximately equal width for each seat adjustment position. The coupling mechanism also fixes the upholstery elements in their particular adjusted positions.
In the vehicle seat according to the present invention, the total seat depth change of the seat cushion is positively subdivided between a plurality of gaps which all have the same gap width. This is dimensioned in such a way that the dimension of a normal pleat is not exceeded even in the case of maximum seat depth. Such relatively narrow gaps, however, cannot be felt when sitting. At the same time, the upholstery elements are fixed in every adjustment position, relative to one another and relative to the seat sub-frame, by a coupling mechanism for adjusting identical gaps. In other words, the upholstery elements are fixed so that they are invariable and cannot be moved in any event by the body weight of the person seated. The occupant of the vehicle therefore has a secure seat and feels better when seated.
An advantageous embodiment of the coupling mechanism, according to the present invention, for restraining the upholstery elements and adjusting constant gap widths provides a plurality of air chambers associated with the upholstery elements, these air chambers being connectable to a compressed air system for inflation and deflation. This embodiment is used preferentially in vehicles with compressed air equipment. When the seat depth is reduced, the upholstery sections are then returned either in accordance with an exemplary embodiment which uses spring elastic return elements when the air chambers are deflated, or by connection to an air suction pump which generates a vacuum in the air chambers.
Another advantageous embodiment for restraining the upholstery elements and adjusting constant gap widths provides coupling means which has a trellis gear with trellis arms connected together via pin-joints, these pin-joints including central pin-joints fixed to either the individual upholstery elements or their support elements.
In certain preferred embodiments, the seat cushion has seat upholstery and an upholstery cover covering the seat upholstery, this upholstery cover extending in one piece over the upholstery elements and having dimensions such that the cover stretches over the seat cushion at maximum gap widths between the upholstery elements. Spring tensioning means are provided which have drawn-in force directed towards an underside of the seat cushion and engage with the upholstery cover in the region of the gaps. An alternative embodiment provides an upholstery cover made of elastic covering material which extends in one piece over the upholstery elements and, in a region of the gaps, is fed around tension rods extending in the gaps between the upholstery elements. These tension rods are held on or near a underside of the upholstery element remote from a seating surface in the guides of the upholstery elements. By means of these alternative measures, folds of the upholstery cover will not appear for any seat depth adjustment of the seat cushion. The upholstery cover is thus, always firmly stretched and gives a seat a visually attractive, smooth surface.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.